Harriet Marcus is concerned about the financing of a home. She saw a small cottage that sells for $$60,000.$ Assuming that she puts $20\%$ down, what will be her monthly payment and the total cost of interest over the cost of the loan for each assumption? $($Use the Table $15\mathrm{.}1)$

Note: Do not round intermediate calculations. Round your answers to the nearest cent.

$\backslash$table$[[,$Monthly payment,Total cost of interest$],[$a$.25$ Years, $5\mathrm{.}50\%,,],[$b$.25$ Years, $6\mathrm{.}00\%,,],[$c$.25$ Years, $6\mathrm{.}25\%,,],[$d$.25$ Years, $6\mathrm{.}50\%,,]]$

e$.$ What is the savings in interest cost between $5\mathrm{.}50\%$ and $6\mathrm{.}50\%?$

Note: Round your answer to the nearest dollar amount.

Interest cost

f$.$ If Harriet uses $30$ years instead of $25$ for both $5\mathrm{.}50\%$ and $6\mathrm{.}50\%,$ what is the difference in interest?

Note: Use $360$ days a year. Round your answer to the nearest dollar amount.